This invention relates to a handle bar fixing device for a bicycle, and more particularly to a handle bar fixing device for a bicycle, which is used for fixing the handle bar to a handle stem.
Generally, the handle stem has at its top a lug extending radially of the stem, the lug having at its utmost end a cylindrical holding portion, in which the handle bar is inserted to be fixed through a fixing device.
The conventional fixing device for the handle bar, as shown in FIG. 4, is so constructed that a cylindrical handle-bar-holding portion a provided at the utmost end of a lug e extending from the handle stem is cut at one side and the opposite cut ends have a pair of flanges b extending radially of the holding portion a, and a bolt c is inserted into the flanges b and tightened to contract the holding portion a in diameter, whereby the handle bar d inserted into the holding portion a is fixed thereto.
Another conventional fixing device, as shown in FIG. 5, is so constructed that the lug e of the handle stem is provided with a chamber f opening into an insertion bore at the holding portion a and housing a pusher h and a cam i, the pusher h having at its one side a cam face g, so that the cam i is screwably moved by a bolt j inserted from the outside of lug e to thereby move the pusher h toward the axis of holding portion a to fix the handle bar d thereto.
Both conventional fixing devices, which have the flanges b or bolt j projecting outwardly, are not desirable from the viewpoint of appearance and safety. Also, the bolt c or j located as shown is not easily turned for control.
Furthermore, the bolts c and j are exposed outward and to the weather which frequently causes them to rust, resulting in difficulty of removing the handle bar for exchange. Especially, in the device shown in FIG. 5, the bolt j, even when not rusted, is screwed to allow the cam i to jam the cam face g, which causes difficulty in unscrewing the bolt j. Also, even when the bolt j is unscrewed to move the cam i backward, the pusher h is not associated with the cam i in the direction of backward movement thereof, and continues to push against the handle bar, resulting in a difficult removal of the handle bar.
In order to overcome the aforesaid problems, this invention has been designed. A main object of the invention is to provide a handle bar fixing device which is simple in construction and capable of being assembled entirely into the handle stem to have a simple appearance. Another object is to ensure a good operation for fixing a handle bar.
Another object of the invention is to provide a handle bar fixing device capable of simply and reliably releasing the fixed handle bar to thereby facilitate removal thereof.
In detail, the handle bar fixing device of the invention is used to fix the handle bar to a cylindrical holding portion provided at the utmost end of a lug extending from the handle stem. At the lug is provided a through bore which extends lengthwise of the lug, opens at one end into the holding portion and at the other end onto one side of the stem body, and has a screw thread in part. A control member having first and second screw threads different in pitch angle and in the direction of screw, is screwed with the through bore by way of the first screw thread. A pusher having a screw member screwable with the second screw thread is supported axially movably only to a first end portion of the through bore opening into the holding portion. The control member is rotated to force the pusher to move lengthwise of the lug, whereby the handle bar inserted into the holding portion is fixed thereto.
In other words, the second screw thread at the control member, which is screwable with the screw member at the pusher, is made larger in pitch angle than the first screw thread screwable with the screw thread at the through bore. When the control member is rotated to screw forward through the first screw thread, a difference is created between screwably moved distances of the control member and the screw member screwing forward together therewith, thereby forcing the pusher to move toward the axis of the holding portion, or the first and second screw threads are made different in the direction of screw, so that the control member is rotated to screw toward the handle stem, while the screw member screws toward the holding member, whereby the pusher is forcibly moved toward the axis of the holding portion. Hence, the thrust of the screw thread is used to ensure fixing of the handle bar to the holding portion and also easy release therefrom.
These and other objects and novel features of the invention will be more apparent from the detailed description and examples which follow.